Using wood ash in the garden - balancing ph.

[Susan BBPM]

A big drive for me in gardening is to do it all for free. This is more about the confidence of knowing that if I CAN'T get what I need in the future that I can continue to grow without it (so I have no qualms about big spends if they're a one off that will last). Anyway, to my question....

We have a woodburner so are producing huge amounts of wood ash. I know that this is good for the garden and contains most of the nutrients that plants need, but I also know it makes the soil very alkaline.

What are the 'rules' for using it?

For example, how much can I add to the compost heap without it causing problems?

Presumably I can dig it into brassica beds....but how much?

Presumably I can neutralize the ph levels by adding sulphur powder and or chips - but again, what ratios? And if I did this could I use it on all my beds or would it still be problematic for some crops?

It may have been on here that someone suggested using it as a weed killer - it'll raise the ph to the point where nothing can grow. But in this case - any thoughts on the risk of it spreading .... especially when garden is on a slope?

I hate the idea of putting all this woodash in the trash!!

 

[YumYum]

If you were to put the wood ash into the compost, then spread that compost over a 3 acre field, it won't have the same effect as putting that same compost pile in a 10x10 bed.

Putting the wood ash in the compost pile might make it stop working, I'm not sure, but I think I would just pile it up somewhere and then spread it out if you need it.

As far as how much it will raise the pH, it isn't the same for every spot. Look at this site. You must know your soils buffer pH to calculate accurately. That basically means the "acid buffer" for lack of better words. The site shows lime but if you click "show help" in the Lime Source Inputs section, it shows the CCE of wood ashes which you can input and play with the calculations just to give a general ideal of how much you might use in a given area.

If you use too much, then you have a ph buffer on the other end of the scale which determines how much acid it takes to lower the pH to a certain level.

 

[Susan BBPM]

If you were to put the wood ash into the compost, then spread that compost over a 3 acre field, it won't have the same effect as putting that same compost pile in a 10x10 bed.

Putting the wood ash in the compost pile might make it stop working, I'm not sure, but I think I would just pile it up somewhere and then spread it out if you need it.

As far as how much it will raise the pH, it isn't the same for every spot. Look at this site. You must know your soils buffer pH to calculate accurately. That basically means the "acid buffer" for lack of better words. The site shows lime but if you click "show help" in the Lime Source Inputs section, it shows the CCE of wood ashes which you can input and play with the calculations just to give a general ideal of how much you might use in a given area.

If you use too much, then you have a ph buffer on the other end of the scale which determines how much acid it takes to lower the pH to a certain level.

That has just wafted right over my head, but you've given me the info I need to go figure out what you mean. Thank you. This seems to be very useful info!!

 

[DirtMechanic]

So figure this idea out..Carbon, Oxygen and Hydrogen are the big 3, NPK follows.

Acidic soils have more loose Hydrogen. Power of H, or pH, and all that, if I express myself clearly enough.

Ashes have K and some P and are highly alkaline.

What do you make of it all? Too much takes a way primary nutrients? To reduce acidity is to reduce the free Hydrogen.

To reduce H is to reduce a primary nutrient. I am curious.

Is this why nothing grows on a burn scar for like 2 years and then it grows like somebody bribed this website?


lol that was a good one.

 

[Oliver Buckle]

I have a large oak tree at the end of the garden which spreads plenty of acidic leaves come Autumn, so I don't worry too much, but a ph kit is easy to use and shouldn't be expensive.

Is this why nothing grows on a burn scar for like 2 years and then it grows like somebody bribed this website?

Not quite true, we made a grid that fitted over four permanent posts in an apple orchard where prunings had been burned in a large bonfire. First year we got moss, then next year some nettles and docks, and on until it returned to grass. We couldn't measure the nutrient levels, but it started really alkaline and gradually washed out back to normal over about four years.

 

[YumYum]

Just another thought to ponder over... I water my garden with city water when needed (well water is likely about the same) so I'm adding carbonates which can make the soils pH go up over time, and it did before I realized what was happening. Someone who only lets the rain water their garden has a lower pH because rain is acidic and contains no minerals or carbonates to raise th pH. To fight this I run a little distilled white vinegar through my driplines.

 

[DirtMechanic]

I have a large oak tree at the end of the garden which spreads plenty of acidic leaves come Autumn, so I don't worry too much, but a ph kit is easy to use and shouldn't be expensive.

Not quite true, we made a grid that fitted over four permanent posts in an apple orchard where prunings had been burned in a large bonfire. First year we got moss, then next year some nettles and docks, and on until it returned to grass. We couldn't measure the nutrient levels, but it started really alkaline and gradually washed out back to normal over about four years.

Thats right, the first year nothing happens.

 

[smitty55]

A big drive for me in gardening is to do it all for free. This is more about the confidence of knowing that if I CAN'T get what I need in the future that I can continue to grow without it (so I have no qualms about big spends if they're a one off that will last). Anyway, to my question....

We have a woodburner so are producing huge amounts of wood ash. I know that this is good for the garden and contains most of the nutrients that plants need, but I also know it makes the soil very alkaline.

What are the 'rules' for using it?

For example, how much can I add to the compost heap without it causing problems?

Presumably I can dig it into brassica beds....but how much?

Presumably I can neutralize the ph levels by adding sulphur powder and or chips - but again, what ratios? And if I did this could I use it on all my beds or would it still be problematic for some crops?

It may have been on here that someone suggested using it as a weed killer - it'll raise the ph to the point where nothing can grow. But in this case - any thoughts on the risk of it spreading .... especially when garden is on a slope?

I hate the idea of putting all this woodash in the trash!!

I use hardwood ashes in my gardens on a yearly basis and absolutely have no issues with ph due to the amount I use. I use just enough of a dusting to cover the soil and then water it in. For my garlic I use it twice, once when I plant in November and then again when my plants are around 18" tall and I'm about to replace my mulch that I removed in early spring. My tomato beds get a good dusting just before planting. For ph to be an issue you'd have to be piling it on thick. Alliums love a shot of ashes as do greens. My apple trees get a yearly dose too and so do my lawns in the winter on top of the snow. One very important thing to remember is to never let your ashes get rained on as all those water soluble nutrients will get leached out. Here's a mix you could do with a recipe for mixing up a solution. You'll love the way he uses the word free lol.

 

[Susan BBPM]

Awesome! Thank you. We use about 3 cubic meters of firewood a year and it seems insane to be putting the ashes out with the garbage

 

[oneeye]

If you add wood ash without a soil test you can run into problems with potassium lock out. Always get a soil test from the soil lab before adding anything to the garden.

 

[oneeye]

What does too much wood ash do to the soil?
Too much ash can increase the soil pH to levels that interfere with plant growth. Repeated, heavy applications to the same spot (as if you used one corner of the yard as an ash dump) can effectively sterilize soil and threaten surface water quality. Google

 

[Susan BBPM]

What does too much wood ash do to the soil?
Too much ash can increase the soil pH to levels that interfere with plant growth. Repeated, heavy applications to the same spot (as if you used one corner of the yard as an ash dump) can effectively sterilize soil and threaten surface water quality. Google

I would guess that over a season we get at most a couple of 5 gallon tubs of ash. It's only a 3kw fire and it leaves very little ash - we only need to clean the tiny pan out once or twice a week. Our entire garden (including front) probably measures 40 square meters. So if we scattered it evenly over the entire garden (including lawns) I think it's going to be a fairly thin coating each year.

Our soil is natrually acidic clay. The actual growing areas (beds, trees) are given garden compost every year (which I believe helps keep things slightly acidic).

 

[oneeye]

That's a lot of ash to me and adding it every year you can run into problems later. When leaves or compost heats up the pH is acidic but when the compost or leaf mold cools the pH is neutral. So adding wood ash every year can have an impact on the nutrient sequence because of the pH. I would skip a year and allow the soil to rest from the wood ash.

 

[Susan BBPM]

After posting I did do the calculations and realized it was more than I thought.

We can get soil testing done in the UK (£40 a go), but the overall approach I am taking is no dig...with the approach I'm following the simple rule applies to all beds - and one inch of compost to the top off the beds each december. Don't worry about the rest as this will result in all plants getting what they need. Tried and tested by many and supposedly works.

But of course, by adding the ash I'm already breaking that rule. So..

I might put some of it into my compost heap. So save the ash in tubs and as I build new compost piles in the summer, layer in the potash. I've read that this helps the worms to break things down quicker. I've also read that the compost heap can safely absorb a lot of wood ash. I now just need to figure out HOW much?

 

[oneeye]

After posting I did do the calculations and realized it was more than I thought.

We can get soil testing done in the UK (£40 a go), but the overall approach I am taking is no dig...with the approach I'm following the simple rule applies to all beds - and one inch of compost to the top off the beds each december. Don't worry about the rest as this will result in all plants getting what they need. Tried and tested by many and supposedly works.

But of course, by adding the ash I'm already breaking that rule. So..

I might put some of it into my compost heap. So save the ash in tubs and as I build new compost piles in the summer, layer in the potash. I've read that this helps the worms to break things down quicker. I've also read that the compost heap can safely absorb a lot of wood ash. I now just need to figure out HOW much?

The best way to know how much to use is by monitoring the soil pH yearly. Get a soil pH test reading yearly. You can do that yourself with a pocket pH meter or have a soil lab do it for you. Do you know how to test the pH of your soil?